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We report the 87Sr optical lattice clock developed at the National Time Service Center.We achieved a closed-loop operation of the optical lattice clock based on 87Sr atoms.The linewidth of the spin-polarized clock peak is 3.9 Hz with a clock laser pulse length of 300 ms,which corresponds to a Fourier-limited linewidth of 3 Hz.The fitting of the in-loop error signal data shows that the instability is approximately 5 × 10-15τ-1/2,affected primarily by the white noise.The fractional frequency difference averages down to 5.7 × 10-17 for an averaging time of 3000 s.